A router is a piece of computer hardware that connects multiple networks together. This piece allows a user to transmit data between different networks. A wireless router is commonly used in individual homes and controls Internet traffic for personal computers.
In the home, the two networks connected by a router are the Internet that comes through the modem from the Internet company, or the wide-area network, and the local-area network of the home. A router can control what is accessed by users on the network and what information leaves the network. This capability makes the router an essential part of network security. Routers can be wired with Ethernet cables or provide wireless Internet through Wi-Fi.
Larger routers are used by ISPs, or Internet service providers, to connect multiple ISPs to one another. Businesses and universities, which have large LANs with many connected devices and need to share large amounts of data, also use larger, more powerful types of routers than the access routers found in personal homes. These larger ones, sometimes called distribution routers, bring together numerous access routers to create a single network where data can be shared. Many routers have other security options as well, such as firewalls.